Lens module and stereo camera

1. A lens module comprising: a tubular body having opposing first and second ends in an axial direction thereof, and an inner periphery, the tubular body comprising first and second openings at the respective first and second ends, each of the first and second openings communicating with an interior of the tubular body, the first opening being configured to enable light to be incident into the tubular body therethrough; a plurality of lenses disposed in the tubular body such that the lenses have a common optical axis; and an eccentricity restriction member, separate from the plurality of lenses, made of an elastic tubular member and having: opposing first and second ends in an axial direction thereof, and an inner periphery and an outer periphery, the first end of the eccentricity restriction member being closer to the first end of the tubular body than the second end of the eccentricity restriction member is, the eccentricity restriction member being coaxially disposed in the tubular body such that: the outer periphery of the eccentricity restriction member is in contact with the inner periphery of the tubular body; and the inner periphery of the eccentricity restriction member surrounds an outer periphery of at least one of the lenses while biasing the outer periphery of the at least one of the lenses toward the common axis, the eccentricity restriction member comprising a holder formed at the first end thereof, the holder being attached to one of the lenses that is closest to the first end of the eccentricity restriction member, wherein a diameter of the outer periphery of the eccentricity restriction member is larger than a diameter of the inner periphery of the tubular body in an unassembled state in which the eccentricity restriction member is not inserted into the tubular body such that the tubular body compresses the eccentricity restriction member in an assembled state in which the eccentricity restriction member is inserted into the tubular body, which biases the outer periphery of the at least one of the lenses toward the common axis.

2. The lens module according to claim 1 , wherein: the eccentricity restriction member is configured such that the first end of the eccentricity restriction member is located to be adjacent to the first end of the tubular body, and the second end of the eccentricity restriction member is located to be adjacent to the second end of the tubular body.

3. The lens module according to claim 2 , wherein the eccentricity restriction member has a predetermined modulus of elasticity, the lens module further comprising: a plurality of spacer rings each made of a material having a predetermined modulus of elasticity that is higher than the modulus of elasticity of the eccentricity restriction member, each of the spacer rings being disposed in the eccentricity restriction member while being interposed between a corresponding adjacent pair of the lenses.

4. The lens module according to claim 3 , further comprising: a securing member attached to the second end of the tubular body and configured to press one of the lenses toward the first end of the tubular body that is closest to the second end of the tubular body to thereby secure the lenses and the ring spacers to the tubular body.

5. The lens module according to claim 1 , wherein: the inner periphery of the eccentricity restriction member surrounds the outer periphery of the at least one of the lenses while biasing the outer periphery of the at least one of the lenses in a direction substantially perpendicular to the common optical axis.

6. The lens module according to claim 1 , wherein: an elasticity of the eccentricity restriction member allows the diameter of the outer periphery of the eccentricity restriction member to be larger than the diameter of the inner periphery of the tubular body when the eccentricity restriction member is separated from the tubular body in the unassembled state such that the outer periphery of the at least one of the lenses is biased toward the common axis upon assembly of the lens module in the assembled state.

7. The lens module according to claim 1 , wherein: the eccentricity restriction member prevents direct contact between each of the plurality of the lenses and the inner periphery of the tubular body when the eccentricity restriction member is inserted into the tubular body in the assembled state.

8. A stereo camera comprising: a housing having an inner hollow container space and a predetermined linear expansion coefficient; and a first lens module at least partly housed in the housing; and a second lens module at least partly housed in the housing, each of the first and second lens modules comprising: a tubular body having opposing first and second ends in an axial direction thereof, an inner periphery, and a predetermined linear expansion coefficient that is identical to the linear expansion coefficient of the housing, the tubular body comprising first and second openings at the respective first and second ends, each of the first and second openings communicating with an interior of the tubular body, the first opening being configured to enable light to be incident into the tubular body therethrough; a plurality of lenses disposed in the tubular body such that the lenses have a common optical axis; and an eccentricity restriction member, separate from the plurality of lenses, made of an elastic tubular member and having opposing first and second ends in an axial direction thereof, and an inner periphery and an outer periphery, the first end of the eccentricity restriction member being closer to the first end of the tubular body than the second end of the eccentricity restriction member is, the eccentricity restriction member being coaxially disposed in the tubular body such that: the outer periphery of the eccentricity restriction member is in contact with the inner periphery of the tubular body; and the inner periphery of the eccentricity restriction member surrounds an outer periphery of at least one of the lenses while biasing the outer periphery of the at least one of the lenses toward the common axis, the eccentricity restriction member comprising a holder formed at the first end thereof, the holder being attached to one of the lenses that is closest to the first end of the eccentricity restriction member, wherein a diameter of the outer periphery of the eccentricity restriction member is larger than a diameter of the inner periphery of the tubular body in an unassembled state in which the eccentricity restriction member is not inserted into the tubular body such that the tubular body compresses the eccentricity restriction member in an assembled state in which the eccentricity restriction member is inserted into the tubular body, which biases the outer periphery of the at least one of the lenses toward the common axis.

9. The stereo camera according to claim 8 , wherein: the eccentricity restriction member is configured such that the first end of the eccentricity restriction member is located to be adjacent to the first end of the tubular body, and the second end of the eccentricity restriction member is located to be adjacent to the second end of the tubular body.

10. The stereo camera according to claim 9 , wherein the eccentricity restriction member has a predetermined modulus of elasticity, the lens module further comprising: a plurality of spacer rings each made of a material having a predetermined modulus of elasticity that is higher than the modulus of elasticity of the eccentricity restriction member, each of the spacer rings being disposed in the eccentricity restriction member while being interposed between a corresponding adjacent pair of the lenses.

11. The lens module according to claim 10 , further comprising: a securing member attached to the second end of the tubular body and configured to press one of the lenses toward the first end of the tubular body that is closest to the second end of the tubular body to thereby secure the lenses and the ring spacers to the tubular body.

12. The stereo camera according to claim 8 , wherein: the inner periphery of the eccentricity restriction member surrounds the outer periphery of the at least one of the lenses while biasing the outer periphery of the at least one of the lenses in a direction substantially perpendicular to the common optical axis.

13. The stereo camera according to claim 8 , wherein: an elasticity of the eccentricity restriction member allows the diameter of the outer periphery of the eccentricity restriction member to be larger than the diameter of the inner periphery of the tubular body when the eccentricity restriction member is separated from the tubular body of each of the first and second lens modules in the unassembled state such that the outer periphery of the at least one of the lenses is biased toward the common axis upon assembly of each of first and second lens module in the assembled state.

14. A lens module comprising: a tubular body having opposing first and second ends in an axial direction thereof, and an inner periphery, the tubular body comprising first and second openings at the respective first and second ends, each of the first and second openings communicating with an interior of the tubular body, the first opening being configured to enable light to be incident into the tubular body therethrough; a plurality of lenses disposed in the tubular body such that the lenses have a common optical axis; a plurality of eccentricity restriction members, separate from each of the plurality of lenses, each of the plurality of eccentricity restriction members made of an elastic tubular member and having opposing first and second ends in an axial direction thereof, and an inner periphery and an outer periphery, each of the eccentricity restriction members being coaxially arranged in the tubular body such that: the outer periphery of the eccentricity restriction member is in contact with the inner periphery of the tubular body; and the inner periphery of the eccentricity restriction member surrounds an outer periphery of a corresponding one of the lenses while biasing the outer periphery of the corresponding one of the lenses toward the common axis, each of the eccentricity restriction members comprising a holder formed at the first end thereof, the holder of each of the eccentricity restriction members being attached to a corresponding one of the lenses; and a securing member attached to the second end of the tubular body and configured to press one of the lenses toward the first end of the tubular body to thereby secure the lenses and the eccentricity restriction members to the tubular body, one of the lenses pressed by the securing member being closest to the second end of the tubular body, wherein a diameter of the outer periphery of each of the eccentricity restriction members is larger than a diameter of the inner periphery of the tubular body in an unassembled state in which each of the eccentricity restriction members is not inserted into the tubular body such that the tubular body compresses each of the eccentricity restriction members in an assembled state in which each of the eccentricity restriction members is inserted into the tubular body, which biases the outer periphery of the corresponding one of the lenses toward the common axis.

15. The lens module according to claim 14 , wherein: the inner periphery of the eccentricity restriction member surrounds the outer periphery of the at least one of the lenses while biasing the outer periphery of the at least one of the lenses in a direction substantially perpendicular to the common optical axis.

16. The lens module according to claim 14 , wherein: an elasticity of the plurality of eccentricity restriction members allows the diameter of the outer periphery of at least one of the plurality of eccentricity restriction members to be larger than the diameter of the inner periphery of the tubular body when at least one of the plurality of eccentricity restriction members is separated from the tubular body in the unassembled state such that the outer periphery of the corresponding one of the lenses is biased toward the common axis upon assembly of the lens module in the assembled state.